AP Biology Chapter 3: Structure and Function of Macromolecules (Independently brush up on Ch 2 and...

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AP BiologyChapter 3: Structure and Function of Macromolecules

(Independently brush up on Ch 2 and Ch 3.1)

Enduring UnderstandingsEnduring Understandings IV. A. Interactions within biological systems lead to complex

properties. 1. The subcomponents of biological molecules and their sequence determine

the properties of that molecule. B. Competition and cooperation are important aspects of

biological systems. 1. Interactions between molecules affect their structure and function.

C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment.

1. Variation in molecular units provides cells with a wider range of functions.

IV. A. Interactions within biological systems lead to complex properties.

1. The subcomponents of biological molecules and their sequence determine the properties of that molecule.

B. Competition and cooperation are important aspects of biological systems.

1. Interactions between molecules affect their structure and function. C. Naturally occurring diversity among and between

components within biological systems affects interactions with the environment.

Macromolecules

Smaller organic molecules join together to form larger molecules macromolecules

4 major classes of macromolecules: carbohydrates lipids proteins nucleic acids

Polymers

Long molecules built by linking repeating building blocks in a chain monomers

building blocks repeated small units

covalent bonds

How to build a polymer

Synthesis joins monomers by “taking” H2O out

one monomer donates OH–

other monomer donates H+ together these form H2O

requires energy & enzymes

enzyme

Dehydration synthesis - Condensation reaction, in which the lost molecule = H2O

Condensation reaction Condensation reaction

Dehydration Synthesis

HO H HO H

How to break down a polymer Digestion

use H2O to breakdown polymers reverse of dehydration synthesis cleave off one monomer at a time

H2O is split into H+ and OH–

H+ & OH– attach to ends requires hydrolytic enzymes releases energy

HydrolysisHydrolysis

enzyme

Discussion

Under what circumstances would you expect to find a cell conducting a great deal of dehydration synthesis?

In which organs or under what circumstances would you expect to find body cells conducting hydrolysis?

Variety of Polymers Every cell has thousands of

varieties of macromolecules These molecules are constructed

from only 40 to 50 common monomers

Analogy: 26 letters of the alphabet can be combined to form millions of words Shortcoming: macromolecules are

much longer than the average word and they can be branched or 3D.

Carbohydrates

a.k.a. wheeee energy! :D

Carbohydrates Carbohydrates are composed of C, H,

Ocarbo - hydr - ate

CH2O)x C6H12O6

Function: energy energy storage raw materials structural

materials

Monomer: sugars (monosaccharide)

sugar sugar sugar sugar sugar sugar sugarsugar

C6H12O6(CH2O)x

Sugars

Most names for sugars end in -ose Classified by number of carbons

6C = hexose (glucose) 5C = pentose (ribose) 3C = triose (glyceraldehyde)

Sugar structure

5C & 6C sugars form rings in solution

Numbered carbons

energy stored in bondsenergy stored in bonds

You’ll see this come back in our DNA unit…

Simple & complex sugars Monosaccharides

simple 1 monomer sugars Ex: glucose, galactose

Disaccharides 2 monomers

Ex: sucrose, lactose

Polysaccharides 3+ monomers

Ex: starch, cellulose, glycogen

Building sugars Dehydration synthesis to form

glycosidic bond

|fructose

|glucose

monosaccharides

|sucrose

(table sugar)

disaccharide

Polysaccharides

Polymers of sugars costs little energy to build easily reversible = release energy

Functions: energy storage

starch (plants) glycogen (animals)

in liver & muscles structure

cellulose (plants) chitin (arthropods & fungi)

Polysaccharide diversity Molecular structure determines function - a major

theme!

Isomers of glucose Different structure = connect to the next monomer in

the chain differently = different 3D structure. Starch - helical. Cellulose - straight, with free OH to

bond to neighboring celluloses = rigid structure!

in starch in cellulose

Cellulose Most abundant organic

compound on Earth herbivores have evolved a

mechanism to digest cellulose most carnivores have not

that’s why they eat meat to get their energy & nutrients

cellulose = undigestible roughage

Helpful bacteria How can herbivores digest cellulose so

well? BACTERIA live in their digestive systems &

help digest cellulose-rich (grass) meals

Ruminants

Discussion In EXACTLY 20 words, summarize the

most important point or points to remember about carbohydrates.

Lipids: Fats & Oils

Lipid Primary Function:

long term energy storageconcentrated energy

Lipids

Lipids are composed of C, H, O long hydrocarbon chains (H-C)

“Family groups” fats phospholipids steroids

Do not form polymers big molecules made of smaller

subunits not a continuing chain

Same as carbohydrates, but different structure = different function!

Structure: glycerol (3C alcohol) + fatty acid

fatty acid = long HC “tail” with carboxyl (COOH) group “head”

dehydration synthesis

enzyme

Building Fats

Triglycerol 3 fatty acids linked to glycerol ester linkage between OH & COOH

hydroxyl carboxyl

Dehydration synthesis

dehydration synthesis

enzyme

Discussion

What kind of molecule would you expect to be hydrophobic - polar or non-polar?

Do you think lipids (such as fats, oils, waxes) are probably polar or non-polar?

Fats store energy Long HC chain

polar or non-polar? hydrophilic or hydrophobic?

Functions: energy storage

2x carbohydrates cushion organs membranes & waterproofing insulates body

think whale blubber!

Discussion Show me a human who doesn’t want to

eat this and I’ll show you a LIAR. LIESSSSSSS

Knowing their major functions, hypothesize: what occurred in evolutionary history that led to humans enjoying the tastes of fatty and sugary foods?

Structure & Function Saturated Fats

All C bonded to H No C=C double bonds

long, straight chain most animal fats solid at room temp.

contributes to cardiovascular disease (atherosclerosis) = plaque deposits

Structure & Function Unsaturated Fats

C=C double bonds in the fatty acids plant & fish fats vegetable oils liquid at room temperature

the kinks made by doublebonded C prevent the molecules from packing tightly together

Discussion Unsaturated fats are widely

considered to be healthier (sometimes called “good fats” for short) than saturated fats.

Why might this be? (Hint: think of their structures, and what they might mean for how easily the body would use them for energy vs. storing them in fat cells)

Phospholipids Structure:

glycerol + 2 fatty acids + PO4

PO4 = negatively charged

Phospholipids Hydrophobic or hydrophilic?

fatty acid tails = PO4 head = split “personality”

interaction with H2O is complex & very important!

“repelled by water”

“attracted to water”

hydrophobic

hydrophillic

Phospholipids in water Hydrophilic heads “attracted” to H2O

Hydrophobic tails “hide” from H2O can self-assemble into “bubbles”

called micelles can also form a phospholipid bilayer Early Earth history - a cell part that self-

assembles!

bilayer

Why is this important?

Phospholipids create a barrier in water define outside vs. inside they make cell membranes!

Steroids

Structure: 4 fused C rings + ??

different steroids created by attaching different functional groups to rings

different structure creates different function

examples: cholesterol, sex hormones

cholesterol

Cholesterol Important cell component

animal cell membranes precursor of all other steroids

including vertebrate sex hormones high levels in blood contribute to

cardiovascular disease

Cholesterol

helps keep cell membranes fluid & flexible

Important component of cell membrane

From Cholesterol Sex Hormones What a big difference a few atoms can make!

most important point or points to remember about lipids.

Nucleic AcidsInformation

storage

proteinsproteins

DNADNA

Nucleic Acids

Function:genetic material

stores informationgenesblueprint for building

proteins DNA RNA proteins

transfers informationblueprint for new cellsblueprint for next

generation

Nucleic Acids

Examples: RNA (ribonucleic acid)

single helix DNA (deoxyribonucleic acid)

double helix

Structure: monomers = nucleotides

Nucleotides

3 parts nitrogen base (C-N ring) pentose sugar (5C)

ribose in RNA deoxyribose in DNA

phosphate (PO4) group

Nitrogen baseI’m the

A,T,C,G or Upart!

Types of nucleotides

2 types of nucleotides different nitrogen bases purines

double ring N base adenine (A) guanine (G)

pyrimidines single ring N base cytosine (C) thymine (T) uracil (U)

Purine = AG“Pure silver!”

Nucleic polymer Backbone

sugar to PO4 bond phosphodiester bond

new base added to sugar of previous base

dehydration synthesis again! polymer grows in one

direction N bases hang off the

sugar-phosphate backboneDangling bases?

Why is this important?

Pairing of nucleotides

Nucleotides bond between DNA strands H bonds purine :: pyrimidine A :: T

2 H bonds G :: C

3 H bonds

Matching bases?Why is this important?

DNA molecule Double helix

H bonds between bases join the 2 strands A :: T C :: G

Like carbohydrates, strands have direction that matters to structure The end with a dangling phosphate (5’)

can’t have any more bases added to it, unlike the other end (3’)

H bonds?Why is this important?

Copying DNA Replication

2 strands of DNA helix are complementary have one, can build other have one, can rebuild the

Matching halves?Why is this

a good system?

Interesting note…

Ratio of A-T::G-C affects stability of DNA molecule 2 H bonds vs. 3 H bonds biotech procedures

more G-C = need higher T° to separate strands

high T° organisms many G-C

parasites many A-T (don’t know why)

Another interesting note… ATP

Adenosine triphosphate

modified nucleotide adenine (AMP) + Pi + Pi

most important point or points to remember about nucleic acids.

ProteinsMultipurpose

molecules

Proteins

Most structurally & functionally diverse group

Function: involved in almost everything enzymes (pepsin, DNA polymerase) structure (keratin, collagen) carriers & transport (hemoglobin, aquaporin) cell communication

signals (insulin & other hormones) receptors

defense (antibodies) movement (actin & myosin) storage (bean seed proteins)

Proteins

Structure monomer = amino acids

20 different amino acids polymer = polypeptide

protein can be one or more polypeptide chains folded & bonded together

large & complex molecules complex 3-D shape

Rubisco

hemoglobin

growthhormones

Amino acids Structure

central carbon amino group carboxyl group (acid) R group (side chain)

variable group different for each amino acid confers unique chemical properties to

each amino acid like 20 different letters of an alphabet can make many words (proteins)

—N—H

HC—OH

|—C—

Building proteins

Peptide bonds covalent bond between NH2

(amine) of one amino acid & COOH (carboxyl) of another

C–N bond

peptidebond

dehydration synthesisH2O

Building proteins Like carbs & nucleic acids,

polypeptides have direction that matters! N-terminus = NH2 end C-terminus = COOH end

repeated sequence (N-C-C) is the polypeptide backbone

can only grow in one direction, N -> C

Protein structure & function

hemoglobin

Function depends on structure 3-D structure

twisted, folded, coiled into unique shape

collagen

pepsin

Primary (1°) structure Order of amino acids in chain

amino acid sequence determined by gene (DNA)

slight change in amino acid sequence can affect protein’s structure & its function even just one amino acid

change can make all the difference! Remember sickle-cell anemia?

lysozyme: enzyme in tears & mucus that kills bacteria

Sickle cell anemia

I’mhydrophilic! I’m hydrophobic!

Just 1out of 146

amino acids!

Non- polar valine “tries tohide” from water of cellby sticking to anotherhemoglobin molecule

Secondary (2°) structure

“Local folding” folding along short sections of

polypeptide interactions between

adjacent amino acids H bonds

weak bonds between R groups

forms sections of 3-D structure -helix -pleated sheet

Secondary (2°) structure

Tertiary (3°) structure

“Whole molecule folding” interactions between distant amino

acids hydrophobic interactions

cytoplasm is water-based

nonpolar amino acids cluster away from water

H bonds & ionic bonds disulfide bridges

covalent bonds between sulfurs in sulfhydryls (S–H)

anchors 3-D shape

Quaternary (4°) structure

More than one polypeptide chain bonded together only then does polypeptide become

functional protein

Collagen = skin & tendon structure Hemoglobin = holds O2

Sequence -> Structure Structure ->

Function

amino acid sequence

peptide bonds

determinedby DNA R groups

H bonds

R groupshydrophobic interactions

disulfide bridges(H & ionic bonds)

3°multiple

polypeptideshydrophobic interactions

Protein denaturation

Unfolding a protein conditions that disrupt H bonds,

ionic bonds, disulfide bridges temperature pH salinity

alter 2° & 3° structure alter 3-D shape

destroys functionality some proteins can return to their

functional shape after denaturation, many cannot

most important point or points to remember about proteins.

Macromolecule Review

Carbohydrates

Structure / monomer monosaccharide

Function energy raw materials energy storage structural compounds

Examples glucose, starch, cellulose,

glycogen

glycosidic bond

Lipids

Structure / building block glycerol, fatty acid, cholesterol, H-C

chains Function

energy storage membranes hormones

Examples fat, phospholipids, steroids

Nucleic acids

Structure / monomer nucleotide

Function information storage

& transfer Examples

DNA, RNA

phosphodiester bond

Proteins

Structure / monomer amino acids levels of structure

Function enzymes defense transport structure signals receptors

Examples digestive enzymes, membrane

channels, insulin hormone, actin

peptide bond

major theme/s in studying biomacromolecules. (And no, wise guy, I don’t mean “they’re hard.”)

AP Biology Chapter 3: Structure and Function of Macromolecules (Independently brush up on Ch 2 and...

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